Revert of Move content's shell connections to the IO thread

services/navigation/navigation.h

Index: services/navigation/navigation.h
diff --git a/services/navigation/navigation.h b/services/navigation/navigation.h
index ded2c7dbf027c329d6c0851783c175cc144870d0..3a731dd600e6e2440c9b8b3e640f0baae51760c6 100644
--- a/services/navigation/navigation.h
+++ b/services/navigation/navigation.h
@@ -5,9 +5,6 @@
 #ifndef SERVICES_NAVIGATION_NAVIGATION_H_
 #define SERVICES_NAVIGATION_NAVIGATION_H_
 
-#include "base/memory/ref_counted.h"
-#include "base/sequenced_task_runner.h"
-#include "content/public/common/connection_filter.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 #include "services/navigation/public/interfaces/view.mojom.h"
 #include "services/shell/public/cpp/interface_factory.h"
@@ -20,7 +17,7 @@
 
 namespace navigation {
 
-class Navigation : public content::ConnectionFilter,
+class Navigation : public shell::Service,
                    public shell::InterfaceFactory<mojom::ViewFactory>,
                    public mojom::ViewFactory {
  public:
@@ -28,9 +25,11 @@
   ~Navigation() override;
 
  private:
-  // content::ConnectionFilter:
-  bool OnConnect(shell::Connection* connection,
-                 shell::Connector* connector) override;
+  // shell::Service:
+  void OnStart(shell::Connector* connector,
+               const shell::Identity& identity,
+               uint32_t instance_id) override;
+  bool OnConnect(shell::Connection* connection) override;
 
   // shell::InterfaceFactory<mojom::ViewFactory>:
   void Create(shell::Connection* connection,
@@ -41,8 +40,6 @@
                   mojom::ViewRequest request) override;
 
   void ViewFactoryLost();
-
-  scoped_refptr<base::SequencedTaskRunner> view_task_runner_;
 
   shell::Connector* connector_ = nullptr;
   std::string client_user_id_;